[KON-591] null error Signed-off-by: Dimitrios Chalepakis <dimitrios.chalepakis@pta.de>

diff --git a/src/app/pages/contacts/contacts-list/contacts-list-column-definition.ts b/src/app/pages/contacts/contacts-list/contacts-list-column-definition.ts
index 0d1d60c..6e4cc71 100644
--- a/src/app/pages/contacts/contacts-list/contacts-list-column-definition.ts
+++ b/src/app/pages/contacts/contacts-list/contacts-list-column-definition.ts

@@ -47,9 +47,11 @@
     colId: 'note',
     headerName: 'Contacts.Note',
     maxWidth: 130,
-    tooltip: params => {
-      if (params.value.length >= 20) {
+    tooltipValueGetter: params => {
+      if (!!params.value && params.value.length >= 20) {
         return params.value;
+      } else {
+        return '';
       }
     },
     filter: 'agTextColumnFilter',